In the coatings industry, resistance to etching by atmospheric acid precipitation ("acid etch resistance") has become a desirable property for coatings, particularly automotive original equipment coatings. Original equipment manufacturers are requiring that coating systems demonstrate acid etch resistance. Several chemistries have been developed that demonstrate acid etch resistance. An example is alkoxysilane chemistry, in which alkoxysilane functional polymers (typically acrylics) self-condense (or additionally react with crosslinking agents) to form crosslinked coatings.
U.S. Pat. No. 5,532,027, to Nordstrom et al. discloses clear film-forming compositions comprising methoxysilane or ethoxysilane functional acrylic polymers. Although such compositions exhibit acid etch resistance, the compositions may not exhibit acceptable storage stability in that the viscosity of the compositions may increase over time.